Organometallics 1982,1, 223-225
Ph2C=CH2
+
HCo(C0)4
ko(CO)4
+
Scheme I c1,Ph&CH36o(C0)4 %-
-
Ph2CCH3
260(co)4
H Co [ C0)4
fast
PhzCHCH3 i~o(CO)~
cO2(co)8
It has been reported that when Ph2CHBr is reacted with C O ~ ( C Oin) ~THF, Ph2CHCHPh2is formed in good yield: The THF disproportionates C O ~ ( C Oto) ~provide [Co(CO),];, and this anion reacts with the bromide to give Ph2CH as an intermediate which couples to the observed dimer. When we repeated this experiment in the presence of HCo(CO),, Ph2CH2was obtained in 95% yield. Apparently the radical intermediate abstracts hydrogen from HCo(CO), faster than it dimerizes. Ph2CHBr in THF reacts with HCO(CO)~ in the absence of added C O ~ ( C O ) ~ to give Ph2CH2,but the reaction is probably initiated by [Co(CO),]- available either from the strongly acidic6 HCo(CO), or from the disproportionation of C O ~ ( C O ) ~ generated from the decomposition of HCo(CO), in THF.6 The hydrogenation of a-methylstyrene with HMII(CO)~, after which Scheme I is modeled, has also been reported to show a CIDNP effect.' The reported second-order rate law, inverse isotope effect, and deuterium exchange between reactants and produds for HMn(CO), reactions with a-methylstyrene are also characteristic of our reactions with HCo(CO),,l suggesting similar mechanisms for hydrogenations with HMn(CO)6 and HCo(CO)& HCo(CO), was prepared as previously described.lb Ph2C=CH2was purchased from the Aldrich Chemical Co. CIDNP effects were observed on a Varian T 60-MHz 'H NMR spectrophotometer. CIDNP Effect with 1,l-Diphenylethylene. A 500-pL aliquot of freshly prepared 0.80 M (0.40 mmol) HCO(CO)~ was injected into a NMR tube capped with a rubber septum and flushed well with CO. The NMR tube was then placed in a C02/acetone bath at -78 OC. The tube was then removed from the bath, and 40 pL (0.22 mmol) of 1,l-diphenylethylene was quickly injected into the HCo(CO), solution. The NMR tube was then shaken vigorously for 2 s, wiped clean, and immediately placed in the NMR cavity at 31 O C . The spectrum is quickly scanned in the methyl proton region in order to observe the transient emission spectrum. The elapsed time between the injection of the olefin and the beginning of the spectrum scan must be 15-25 s or only an absorption spectrum will be observed. The entire reaction is over in about 60 s. Reaction of HCO(CO)~/CO(CO),-with Bromodiphenylmethane. In a 200-ml round-bottom flask well flushed with CO was placed a 78-mL THF solution of 0.185 M (14.0 mmol) HCo(CO)& To the solution was added 2.4 g (4.9 mmol) of C O ~ ( C Ofollowed )~ by the addition of 1.2 g (4.9 mmol) of bromodiphenylmethane dissolved in 5 mL of THF. The solution was stirred for 1 2 h at room temperature. The solvent was then evaporated and the residue redissolved in 70 mL of CH2C12. To this solution was then added dropwise 5 mL of ethylenediamine. The solution was then washed with H20, 2% aqueous HC1, and saturated aqueous NaCl before drying over CaClzand filtering. Evaporation of the solvent gave a clear oil, 0.78 g (95% yield). Analysis by lH NMR showed it to be essentially
.
223
(4) D. Seyferth and M. D. Miller, J. Organomet. Chem., 38,373 (1972). (5) T. E. Nalesnik and M. Orchin, J. Organomet. Chem., 212, C16
(l981\. - - - -,. (6) M. V. McCabe, J. F. Terrapane, and M. Orchin, Ind. Eng. Chem. Prod. Res. Dev., 14, 281 (1975).
(7) R. L. Sweany and J. Halpern, J. Am. Chem. SOC.,99,8335 (1977).
Figure 1. 'H NMR spectr~(a) emission spectrum of Ph2CHCH3; (b) absorption spectrum of Ph2CHCH3observed 20 s after a; (c) spectrum of Ph2CHCH3with spinning side band of CH2C1,.
pure diphenylmethane. 'H NMR (CDClJ: 6 7.1 (s, 10, phenyls), 3.9 (s, 2, methylene). When the above reaction was repeated in the absence of added C O ~ ( C O an ) ~ ,80% yield of PhzCH2was obtained; no coupled product could be detected ('H NMR). Registry No.HCo(CO),, 16842-03-8; Co2(C0),,, 10210-68-1; 1,ldiphenylethylene, 530-48-3; bromodiphenylmethane, 776-74-9.
Intermetalllc Chalcogenide Atom Transfer and the Synthesis of 1,4-[(CH9C5H4)2Tl]2S4 C. Mark Bollnger, John E. Hoots, and Thomas B. Rauchfuss' School of Chemical Sciences, University of Illinois, Urbana, Illinois 6 180 1 Received September 1, 198 1
Summary: (C5H4R),TiE5(R = H, CH,; E = S, Se) efficiently transfer a dichalcogenide fragment to [ Ir(Ph,PCH2CH2PPh2),]CI affording Ir"*E, complexes and in one case 1,4-[(C5H4CH3),Ti],S4. The unique Ti,S4 heterocycle can also be prepared via the PBu, desulfurization of (C5H,CH,),TiS5.
This report describes a new intermetallic atom transfer reaction' and the synthesis of a very unusual organotransition metal chalcogenide. The key reagents employed in this study are the dicyclopentadienyltitanium(1V) pentachalcogenides whose structures are composed of metallapentachalogenide rings.2 The reactivity of these (1) For other examples of intermetallic atom transfer reactions see: Templeton, J. L.; Ward, B. C.; Chen, G. J.-J.; McDonald, J. W.; Newton, W. E. Inorg. Chem. 1981,20, 1248-1253. Reynolds, J. G.; Holm, R. H. Inorg. Chem.1981,20, 1873-1878. (2) Epstain, E. F.; Bernal, I. J. Organomet. Chem. 1971,26,229-245. Muller, K. G.; Petersen, J. L.; Dahl, L. F. Ibid. 1976, 111, 91-112.
0 1982 American Chemical Society
224 Organometallics, Vol. 1, No. 1, 1982
compounds has been found to contrast sharply with that of the cyclo-octachalcogenides.3
l a , E = S, R = H lb, E = S,R = CH, 2a, E = Se, R = H 2b, E = Se, R = CH,
Equimolar quantities of la or l b and [I~(dppe)~]Cl (dppe = 1,2-bis(diphenylphosphino)ethane)3,4 were found to react efficiently in dichloromethane solution (25 "C, 4 h). After solvent evaporation, washing with THF, and recrystallization of the residue from CH2C12-Et20,a 60% yield of orange, crystalline [Ir(dppe)2S2]C15was realized. The identity of this product was confirmed by detailed comparison of its 360-MHz 'H NMR spectrum with that of the same compound prepared from 3 and c-Spe The efficient synthesis of [Ir(dppe)2Se2]C1by an analogous procedure from 2a and 2b is particularly notable since the published procedure5 using c-Se8proceeds very sluggishly (eq 1). This result illustrates the utility of pentaselenides
,*,
[Iridppe),ICl
[Ir(dppe),Se,lCl
(1)
2a and 2b as conveniently reactive and soluble (8.3 X lo9 and 1.0 X 1W2 M, respectively, in CH2C12at 23 OC') sources of elemental selenium. In contrast, c-Se8 is practically insoluble in useful organic solvents (
